A study of the extraction of cobalt II ions from an aqueous growing drop into a continuous medium of di-2-ethylhexylphosphoric acid (D2EHPA) is made. The apparatus for this technique is described and a flow injection analysis method for measuring the cobalt remaining in the aqueous phase has been developed. In this study the feed concentration of cobalt has varied between 8.48 x 10-3 and 16.97 x 10-3 mole 9-1. The D2EHPA held in n-heptane, has been altered between 0.143 and 2.41 mole P. Also, pH has been adjusted between 3.10 and 4.44. The principal temperature applied to this study was 25 ±0.5*C. Acetate buffers have been used, but it is shown by calculation that about 70% of the cobaltous ion is in an uncomplexed form. The kinetics of the extraction have been modelled using a method based upon reaction in an aqueous zone near to the liquid-liquid interface with diffusion of species towards and away from the interface. This model provided a fundamental parameter 01 which incorporates the chemical rate constant kR, the D2EHPA partition coefficient PHR, the acid dissociation constnat KD for D2EHPA and the metal ion diffusivity in the interface diffusion region. The results have been compared with those of other workers who studied the transfer of cobalt into an organic drop from an aqueous continuum. The diffusion controlling film is the aqueous one. The rate constant for, the extraction reaction equation is, from this work, kR - 106.34 M3 kmol-1 sec-1 which can be compared with that found by another worker using the reverse transfer system, i. e. kR - 106.18 m3 kmol-I sec-i. . Finally, the mass transfer coefficients were found to change with varying feed concentrations and pH, this is also in agreement with other workers who have studied different liquid-liquid systems.

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New approaches to the analysis of trace metal concentrations in seawater have the potential to advance the field of oceanography and provide a more comprehensive understanding of the marine biogeochemical cycles of trace metals and the processes regulating these cycles. Traditional oceanographic methods of trace metal analysis were developed several decades ago using benchtop liquid-liquid extraction (Danielson et al., 1978; Kinrade and Van Loon, 1974; Miller and Bruland, 1994; Moffett and Zika, 1987). More modern techniques utilize flow based solid phase extraction to eliminate the high ionic strength matrix to determine dissolved concentrations with great accuracy and precision but do not allow for the determination of metal speciation in solution (Wells and Bruland, 1998). The method developed here measures oceanographically relevant concentrations of copper (Cu) in seawater via chemiluminescence (Marshall et al., 2003 and Coale et al., 1992) and micro-molar levels of silver (Ag) colorimetrically after automated liquid-liquid extraction. The Zone Fluidics (Marshall et al., 2003) analyzer for trace Cu determined SAFe D2 standard seawater (www.geotraces.org) to be 1.77 nM Cu comparable to the expected consensus value. The method was used to determine dissolved Cu depth profiles for major stations along the Line P Time-series transect (48N 125W - 50N 145W) in the Pacific Ocean during February 2011. This method consumes less than 200 µL of sample and reagents and is performed in less than 3 minutes making it suitable for ship or lab based analysis. / Graduate / 0485 / 0425 / cschwang11@gmail.com

<p> This report covers two topics. First is the development of computer programs to carry out the calculations needed to determine the control policy to bring a process from one set of steady state conditions to another. Examples of the implementation of control policies for a liquid-liquid extraction column are included. Suggestions have been made for means of decreasing the calculation time and for means of increasing the size of problem that may be solved. </p> <p> The second part discusses an initial project of using a Supernova computer as a direct control computer. Characteristics of direct digital control are illustrated using an analog simulation of the extraction unit as the controlled process. </p> / Thesis / Master of Engineering (MEngr)

With many processing advantages, electrophoretic deposition (EPD) has been chosen as the fabrication technique for inorganic-organic nanocomposites. However, before the EPD process, avoiding the particles agglomeration is considered a necessary perquisite for the success of fabrication. In this research, two different liquid-liquid extraction methods, one is one-step and the other is two-step, were developed to solve the agglomeration problem of inorganic particles. The adsorption mechanisms of the extractors and extraction mechanisms were investigated during this work. The strong adsorptions provided by –OH groups of the extractors and further Schiff base reaction allowed for the process of extraction. In the fabrication, polyelectrolytes acted as the film forming and charging agents. Relatively stable suspensions with extracted inorganic particles were prepared for the EPD of inorganic-organic nanocomposites. The thickness of deposited films is proportional to the concentration of the suspension and deposition time. With the addition of flame retardant inorganic particles, the prepared nanocomposite films showed an enhanced flame retardant performance. / Thesis / Master of Applied Science (MASc)

Fresh water in Kuwait is produced by non- conventional methods. About 95% of this water comes from desalinated seawater using multi-stage flash distillation technique and the remainder comes from underground brackish water. The blended water containes organic, inorganic and trace metal impurities within the recommended international standard limits. The purpose of this work is to identify the source of selected trace metals present in the drinking water in Kuwait. Chromium, copper, iron, lead, manganese, nickel, vanadium and zinc have been analysed using atomic absorption spectroscopy (AAS) and inductively coupled plasma mass spectroscopy (ICPMS). Efforts were made to improve the preconcentration of the selected metals and their separation from the high concentration of salts in seawater which affect the accuracy and cause major interference in the analysis. Solid-liquid extraction (chelex-100 resin) and liquid-liquid extraction (methyl iso-butyl ketone and freon) with and without back-extraction into nitric acid were investigated. Liquid-liquid extraction without back-extraction proved to give optimum recovery of the selected metals. Results confirmed that both AAS and ICP-MS are suitable for the analysis of trace metals in Kuwait's waters. Although AAS technique proved to be more accurate in analysing the selected metals than ICP-MS, the latter was adopted since its accuracy is acceptable (1.1-4.4%) and it is easier and faster than the former technique. The study revealed that the source of copper, iron, nickel and zinc is the construction materials of the distillation plants, while the source of lead and vanadium is the brackish water. Manganese and chromium concentrations are very low in all sources. No direct relationship between the metal concentration in the seawater and the distillate could be deduced.

This research study successfully completed three objectives: 1) validate liquid-liquid, supported-liquid, and solid-phase extractions for the quantitation of three barbiturates (amobarbital, butalbital, and phenobarbital) in blood and urine using liquid chromatography-tandem mass spectrometry; 2) to compare the efficiency and effectiveness among methods in accomplishing extraction of barbiturates under the laboratory setting at Boston University School of Medicine; and 3) to report all the analytical data to RTI International for interlaboratory comparison. For the validation study, a six-point linear calibration model (20-2000 ng/mL) with inversely weighted concentration (1/x) was reproducible in all three sample preparation methods for both blood and urine with r2 greater than or equal to 0.994. Bias and precision evaluated from three controls throughout the range of the curve were within ±20% and ±20%CV, respectively. Neither carryover nor interference was observed. Detection limits were evaluated down to 5 ng/mL depending on the extraction procedure. Samples were able to be diluted up to 50 times prior to instrumental analysis. Samples were stable on autosampler at room temperature up to 72 hours after their initial analysis. Recovery of barbiturates from blood and urine all ranged from 45% to 86%. The effect of ionization suppression or enhancement was found to have minimal impact on the validation. For choosing the most suitable method quantifying barbiturates, efficiency and effectiveness were studied. Efficiency evaluates the time and ease of sample preparation required to prepare a sample for analysis. Supported-liquid extraction was found to be the most efficient method for extracting barbiturates as it required the least amount of time to perform and could be easily automated with minimal training. Effectiveness is an assessment of one’s ability to selectively recover target analyte at a reasonably low concentration. By considering a method’s recovery, extract cleanliness, detection limits, and reproducibility, liquid-liquid extraction was the best at quantifying barbiturates in blood and supported-liquid extraction was the most suitable method for extracting barbiturates from urine. For interlaboratory comparison, all the data collected has been reported to RTI International. These findings can be used for examining the overall reliability and reproducibility of the validated methods. Results obtained can also be used to explore the possibility for streamlining sample preparation in the forensic laboratory, and hence reducing the case backlog.